This proposal continues a long-term investigation of the control of movement when proprioception is absent. It focuses on two major issues in deafferentation research: which central structures are involved in the mediation of purposive movements after proprioception is abolished in the responding limb, and whether intradural section of dorsal roots does in fact remove all sensory input. We plan to ablate dorsal solumn nuclei and/or ventral lateral nucleus of the thalamus either at the time of deafferentiation (C2-T3) or after some postoperative recovery of purposive movement has taken place. Monkeys will be tested on a recently developed motor task which involles touching a sequence of briefly lit buttons without visual guidance of the deafferented limb. Performance of deafferents with and witoout superimposed lesions will be compared. To test whether proprioceptive input is still available after dorsal rhizotomy, we propose to train intact monkeys in a proprioceptive discrimination involving movement and/or position of various forelimb joints, and retest after forelimb deafferentation. These data will provide an additional basis upon which the deafferentation literature, including our own, can be evaluated. Furthermore, we expect that our findings on the locus of structures involved in the central monitoring of movement in the absence of peripheral feedback will broaden our understanding of processes involved in the recovery of motor function when peripheral sources of information are excluded.